package com.itheima;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.IOException;

@WebServlet("/servltDemo04")
public class ServltDemo04 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String realPath = getServletContext().getRealPath("/img/hm.png");
        //1.创建字节流对象，关联读取文件
        BufferedInputStream bis = new BufferedInputStream(new FileInputStream(realPath));
        //2.设置响应头支持的类型
        resp.setHeader("Content-Type","application/octet-stream");
        //3.设置响应头一下载方式打开附件
        resp.setHeader("Content-Disposition","attachment;filename=hm.png");
        //4.获取字节输出流对象
        ServletOutputStream os = resp.getOutputStream();
        //5.循环读写
        byte[] bytes = new byte[1024];
        int len;
        while ((len=bis.read(bytes))!=-1){
            os.write(bytes,0,len);
        }

        //6.释放资源
        bis.close();
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}
